The Zaza Formation is a geological formation located in

Buryatia Buryatia, officially the Republic of Buryatia (russian: Республика Бурятия, r=Respublika Buryatiya, p=rʲɪsˈpublʲɪkə bʊˈrʲætʲɪjə; bua, Буряад Улас, Buryaad Ulas, , mn, Буриад Улс, Buriad Uls), is ...

(

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

). It dates to the

Lower Cretaceous Lower may refer to: *Lower (surname) *Lower Township, New Jersey *Lower Receiver (firearms) *Lower Wick Lower Wick is a small hamlet located in the county of Gloucestershire, England. It is situated about five miles south west of Dursley, eight ...

period. It is

Aptian The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), a ...

in age and consists of

sandstones Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) b ...

, siltstones, marls and bituminous

shales Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especiall ...

, deposited in a stratified lake. It is situated on a large granite plateau in the NE of Buryatia.Zherikhin, V.V., Mostovski, M.B., Vrsansky, P., Blagoderov, V.A. and Lukashevich, E.D. 1999
The unique Lower Cretaceous locality of Baissa and other contemporaneous insect-bearing sites in North and West Transbaikalia
''Proceedings of the First Palaeoentomological Conference, Moscow, 1998''. Bratislava: Amba Projects, pp. 185-192. The formation is known for its numerous compression fossils of many varieties of insect found predominantly at the Baissa locality, located on the banks of the Vitim River. Insects are found in multiple beds throughout the succession, predominantly in the finer grained facies, the preservation of insect fossils is variable between beds, with good preservation in marl and poor preservation in shale beds.

See also

References

Further reading